ASTR 1150 Lecture Notes - Lecture 5: Protoplanetary Disk, Orion Nebula, Protostar
Document Summary
Astr 1150 - lecture five: the birth of stars and main sequence. Star formation is taking place right now. Rate of star formation has slowed over time. Primarily in the spiral arms of galaxies. As particles warm up they tend to spread further apart (think of how gasses expand with heat) and lower the local density. In order for a cloud of gas and dust to achieve sufficiently high density to form a star it needs to initially be a low temperature. One a region of gas and dust cool enough it will begin to gain additional matter through gravity until it is so massive that the material does have enough engergy to hold it up against gravitational collapse. Liquids and gasses also ten to spread out and flatten as they are spun. As the spinning collapsing cloud gets smaller and smaller due to gravity (shrinks by many orders of magnitude) the center begins to achieve extremely high density.
